Development of a matrix solid-phase dispersion method for the determination of polycyclic aromatic hydrocarbons in sewage sludge samples

A new, single-step extraction and purification method based on matrix solid-phase dispersion (MSPD) was developed to determine 17 polycyclic aromatic hydrocarbons (PAHs) in sewage sludge samples. The MSPD method consists of sample homogenisation, exhaustive extraction and clean-up by a single process. The different operational parameters of the method, such as the type of dispersant, type and amount of additives, clean-up co-sorbent and extractive solvent were evaluated. Reversed-phase (C18) and polymeric (Oasis HLB and Oasis MAX) materials, as well as normal phase sorbents (Florisil, silica, neutral alumina) and an inert support (sand) were tested to assess the sorbents effect on the yield and selectivity of the MSPD process. Analysis of extracts was performed by high performance liquid chromatography (HPLC) coupled with fluorescence detection.Quantification limits obtained for all of these considered compounds (between 0.0001 and 0.005 μg g⁻¹ dry mass) were well below of the limits recommended in the EU. The extraction yields for the different compounds obtained by MSPD ranged from 76.3% to 103.6%. On the other hand, the extraction efficiency of the optimised method is compared with that achieved by microwave-assisted extraction and the method was applied to the analysis of real sewage sludge samples. A certified reference material (sewage sludge (BCR 088)) and a reference material (sewage sludge (RTC-CNS312-04)) were used to validate the proposed method.     

Cooling/heating-assisted headspace solid-phase microextraction of polycyclic aromatic hydrocarbons from contaminated soils

A simple, low-cost, and effective cooling/heating-assisted headspace solid-phase microextraction (CHA–HS–SPME) device, capable of direct cooling the fiber to low temperatures and simultaneous heating the sample matrix to high temperatures, was fabricated and evaluated. It was able to cool down the commercial and handmade fibers for the effective tapping of volatile and semi-volatile species in the headspace of complex solid matrices, with minimal manipulation compared with conventional SPME. The CHA–HS–SPME system can create large temperature gaps (up to 200 °C) between the fiber and the sample matrix, because the cooling process is directly applied onto the fiber.     

Evaluation of matrix solid‐phase dispersion extraction for the determination of polycyclic aromatic hydrocarbons in household dust with the aid of experimental design and response surface methodology

A simple, fast, and inexpensive procedure for sample preparation based on matrix solid‐phase dispersion was developed for the determination of Environmental Protection Agency 16 priority polycyclic aromatic hydrocarbons in indoor dust samples. Parameters that affect the extraction efficiency such as type of dispersant, elution solvent, and solvent volume were evaluated and optimized with the aid of experimental design and response surface methodology. Analysis was performed by HPLC coupled with UV‐Vis diode array detector (UV‐DAD). For verification, a GC coupled with a mass spectrometer in SIM mode was also applied. Recoveries obtained were from 53 to 120% for all target analytes with detection limits ranging from 0.2 to 10 ng/g and 0.2 to 2 ng/g for LC‐UV‐DAD and GC‐MS, respectively. The optimized method was used for the analysis of 11 household dust samples collected from private houses.     

同位素稀释三重串联四级杆质谱法测定鱼组织中24种多环芳烃

采用气相色谱-三重串联四级杆质谱联用技术测定了鱼组织中24种多环芳烃(PAHs).将冻干鱼组织样品加入同位素内标后,用加速溶剂萃取法(ASE)进行提取,提取液采用凝胶排阻色谱(GPC)和固相萃取(SPE)联用进行净化.采用二氯甲烷为提取溶剂,100℃下提取,以二氯甲烷作为GPC的流动相,在3.5 mL/min流速下,收...     

Determination of polycyclic aromatic hydrocarbons in food samples by automated on-line in-tube solid-phase microextraction coupled with high-performance liquid chromatography-fluorescence detection

A simple and sensitive automated method, consisting of in-tube solid-phase microextraction (SPME) coupled with high-performance liquid chromatography-fluorescence detection (HPLC-FLD), was developed for the determination of 15 polycyclic aromatic hydrocarbons (PAHs) in food samples. PAHs were separated within 15 min by HPLC using a Zorbax Eclipse PAH column with a water/acetonitrile gradient elution program as the mobile phase. The optimum in-tube SPME conditions were 20 draw/eject cycles of 40 μL of sample using a CP-Sil 19CB capillary column as an extraction device. Low- and high-molecular weight PAHs were extracted effectively onto the capillary coating from 5% and 30% methanol solutions, respectively. The extracted PAHs were readily desorbed from the capillary by passage of the mobile phase, and no carryover was observed. Using the in-tube SPME HPLC-FLD method, good linearity of the calibration curve (r > 0.9972) was obtained in the concentration range of 0.05–2.0 ng/mL, and the detection limits (S/N = 3) of PAHs were 0.32–4.63 pg/mL. The in-tube SPME method showed 18–47 fold higher sensitivity than the direct injection method. The intra-day and inter-day precision (relative standard deviations) for a 1 ng/mL PAH mixture were below 5.1% and 7.6% (n = 5), respectively. This method was applied successfully to the analysis of tea products and dried food samples without interference peaks, and the recoveries of PAHs spiked into the tea samples were >70%. Low-molecular weight PAHs such as naphthalene and pyrene were detected in many foods, and carcinogenic benzo[a]pyrene, at relatively high concentrations, was also detected in some black tea samples. This method was also utilized to assess the release of PAHs from tea leaves into the liquor.     

Evaluation of solid-phase microextraction conditions for the determination of polycyclic aromatic hydrocarbons in aquatic species using gas chromatography

This paper describes a headspace solid-phase microextraction (HS-SPME) procedure coupled to gas chromatography with mass spectrometric detection (GC–MS) for the determination of eight PAHs in aquatic species. The influence of various parameters on the PAH extraction efficiency was carefully examined. At 75 °C and for an extraction time of 60 min, a polydimethylsiloxane–divinylbenzene (PDMS/DVB) fiber coating was found to be most suitable. Under the optimized conditions, detection limits ranged from 8 to 450 pg g⁻¹, depending on the compound and the sample matrix. The repeatability varied between 7 and 15% (RSD). Accuracy was tested using the NIST SRM 1974b reference material. The method was successfully applied to different samples, and the studied PAHs were detected in several of the samples. Figure Headspace SPME sampling followed by GC–MS facilitates routine monitoring of PAHs in aquatic species     

Determination of trace amounts of polycyclic aromatic hydrocarbons in soil

A method for monitoring the contamination of soil with polycyclic aromatic hydrocarbons (PAHs) is introduced. Drying at elevated temperature is omitted to avoid losses of the more volatile constituents (primarily naphthalene). The soil sample, including its natural water content, is extracted with 2-methoxyethanol and cleaned up using a disposable C₈ cartridge and the PAHs are eluted with pentane, concentrated and measured by capillary gas chromatography with flame ionization detection. Determination limits between 15 and 35μg kg^?1 are obtained and the recovery is 80–90% measured at the 125 μg kg^?1 spike level, except for naphthalene (66%). Special attention is given to the design of the spiking technique, which simulates natural incorporation as far as possible, takes account of evaporation losses and therefore allows “real” recovery rates to be determined.     

On-line solid-phase extraction and high performance liquid chromatography determination of polycyclic aromatic hydrocarbons in water using polytetrafluoroethylene capillary

Naphthalene, biphenyl, acenaphtene, anthracene and pyrene were extracted from water samples using inner walls of polytetrafluoroethylene capillary. Optimum conditions for sorption, desorption and heart-cutting of the analyte zone were found. Combined on-line solid-phase extraction and HPLC method for determination of these compounds was proposed. Limits of detection were: (μg L⁻¹): 0.4 (naphthalene), 0.3 (biphenyl), 0.6 (acenaphtene), 0.2 (anthracene) and 0.1 (pyrene).     

Analysis of polycyclic aromatic hydrocarbons in fish: evaluation of a quick,easy, cheap,effective, rugged,and safe extraction method

QuEChERS method was evaluated for extraction of 16 PAHs from fish samples. For a selective measurement of the compounds, extracts were analysed by LC with fluorescence detection. The overall analytical procedure was validated by systematic recovery experiments at three levels and by using the standard reference material SRM 2977 (mussel tissue). The targeted contaminants, except naphthalene and acenaphthene, were successfully extracted from SRM 2977 with recoveries ranging from 63.5–110.0% with variation coefficients not exceeding 8%. The optimum QuEChERS conditions were the following: 5 g of homogenised fish sample, 10 mL of ACN, agitation performed by vortex during 3 min. Quantification limits ranging from 0.12–1.90 ng/g wet weight (0.30–4.70 μg/L) were obtained. The optimized methodology was applied to assess the safety concerning PAHs contents of horse mackerel (Trachurus trachurus), chub mackerel (Scomber japonicus), sardine (Sardina pilchardus) and farmed seabass (Dicentrarchus labrax). Although benzo(a)pyrene, the marker used for evaluating the carcinogenic risk of PAHs in food, was not detected in the analysed samples (89 individuals corresponding to 27 homogenized samples), the overall mean concentration ranged from 2.52 ± 1.20 ng/g in horse mackerel to 14.6 ± 2.8 ng/g in farmed seabass. Significant differences were found between the mean PAHs concentrations of the four groups.     

Fluidized-bed extraction of polycyclic aromatic hydrocarbons from contaminated soil samples

Summary Due to the carcinogenity and ubiquity of polycyclic aromatic hydrocarbons in the environment they are of ongoing interest to analytical chemistry. In this study, a comparison of the classic Soxhlet extraction and, fluidized-bed extraction, has been conducted. The extraction of polycyclic aromatic hydrocarbons by this technique has been optimized considering as experimental variables the variation of the number of extraction cycles and the holding time after reaching the heating temperature by means of a surface response design. The significance of the operational parameters of the fluidized-bed extraction on the performance characteristics has been investigated. For the determination of the analytes a selective clean-up of the extracts followed by a fast gas chromatography method with mass spectrometric detection was used, resulting in low limits of detection (0.2 pg μL⁻¹). The accuracy of the complete analytical method was established by extraction and analysis of reference materials.     

Rapid SPE-HPLC determination of the 16 European priority polycyclic aromatic hydrocarbons in olive oils

Polycyclic aromatic hydrocarbons (PAHs) are a large class of organic compounds. It has been established that the main source of exposure to these compounds for human beings is through food, particularly fats and oils, due to the lipophilic nature of these polycyclic compounds. The aim of this work was to optimise and validate a method involving SPE and HPLC for rapid determination of the 16 European Union (EU) priority PAHs (required by the Recommendation 2005/108/EC) in vegetable oils. Two spectrofluorometric detectors and a UV-Visible detector in series were used to identify and quantify the target compounds. Linearity, recoveries, LOD, and LOQ were found to be in agreement with the performance criteria for benzo[a]pyrene (BaP) analysis as required by the Commission Directive 2005/10/EC, and satisfactory for all the compounds of interest, except for cyclopenta[c,d]pyrene, which presented a very low signal in the UV. Optimised chromatographic conditions for the separation of 25 PAHs, comprising both EPA and EU priority PAHs plus benzo[e]pyrene and benzo[b]chrysene, have been also proposed.     

Application of sulfur microparticles for solid-phase extraction of polycyclic aromatic hydrocarbons from sea water and wastewater samples

The application of sulfur microparticles as efficient adsorbents for the solid-phase extraction (SPE) and determination of trace amounts of 10 polycyclic aromatic hydrocarbons (PAHs) was investigated in sea water and wastewater samples using high performance liquid chromatography coupled with an ultraviolet detector (HPLC–UV). Parameters influencing the preconcentration of PAHs such as the amount of sulfur, solution flow rate and volume, elution solvent, type and concentration of organic modifier, and salt effect were examined. The results showed that at a flow rate of 10 mL min⁻¹ for the sample solutions (100 mL), the PAHs could be adsorbed on the sulfur microparticles and then eluted by 2.0 mL of acetonitrile. For HPLC–UV analysis of extracted PAHs, the calibration curves were linear in the range of 0.05–80.0 μg L⁻¹; the coefficients of determinations (r²) were between 0.9934 and 0.9995. The relative standard deviations (RSDs) for eight replicates at two concentration levels (0.5 and 4.0 μg L⁻¹) of PAHs were lower than 7.3%, under optimized conditions. The limits of detection (LODs, <!-- no-mfc -->S/N<!-- /no-mfc --> = 3) of the proposed method for the studied PAHs were 0.007–0.048 μg L⁻¹. The recoveries of spiked PAHs (0.5 and 4 μg L⁻¹) in the wastewater and sea water samples ranged from 78% to 108%. The simplicity of experimental procedure, high extraction efficiency, short sample analysis, and using of low cost sorbent demonstrate the potential of this approach for routine trace PAH analysis in water and wastewater samples.     

Development of a focused ultrasonic-assisted extraction of polycyclic aromatic hydrocarbons in marine sediment and mussel samples

Focused ultrasonic-assisted extraction (FUSE) is a new and particular technique based on the cavitation effect. In this work, the focused ultrasound assisted extraction was studied and developed for the extraction of polycyclic aromatic hydrocarbons from marine sediments and mussel tissues. The variables influencing the extraction (amplitude of the ultrasound pulse, the extraction time and the solvent) were studied by a full factorial design and a central composite design. As a result, flat response surfaces were obtained and the most convenient conditions were 45% of ultrasound amplitude, 120 s of extraction time and 5 mL of acetone. Both accuracy and precision of the method were evaluated by means of two certified reference materials (marine sediment and mussel tissue) and the results were also compared to those obtained by microwave assisted extraction.     

Headspace solvent microextraction and gas chromatographic determination of some polycyclic aromatic hydrocarbons in water samples

Headspace solvent microextraction (HSME) was shown to be an efficient preconcentration method for extraction of some polycyclic aromatic hydrocarbons (PAHs) from aqueous sample solutions. A microdrop of 1-butanol (as extracting solvent) containing biphenyl (as internal standard) was used in this investigation. Extraction occurred by suspending a 3 μl drop of 1-butanol from the tip of a microsyringe fixed above the surface of solution in a sealed vial. After extraction for a preset time, the microdrop was retracted back into the syringe and injected directly into a GC injection port. The effects of nature of extracting solvent, microdrop and sample temperatures, stirring rate, microdrop and sample volumes, ionic strength and extraction time on HSME efficiency were investigated and optimized. Finally, the enrichment factor, dynamic linear range (DLR), limit of detection (LOD) and precision of the method were evaluated by water samples spiked with PAHs. The optimized procedure was successfully applied to the extraction and determination of PAHs in different water samples.     

Recent developments in matrix solid-phase dispersion extraction

Matrix solid-phase dispersion is a sample preparation strategy widely applied to solid, semisolid or viscous samples, including animal tissues and foods with a high lipidic content. The process consists in blending the matrix onto a solid support, allowing the matrix cell disruption and the subsequent extraction of target analytes by means of a suitable elution solvent. First introduced in 1989, MSPD employment and developments are still growing because of the feasibility and versatility of the process, as evidenced by the several reviews that have been published since nineties. Therefore, the aim of the present review is to provide a general overview and an update of the last developments of MSPD.     

Characterization of polycyclic aromatic hydrocarbons in environmental samples by selective fluorescence quenching

Selective fluorescence quenching is used to profile polycyclic aromatic hydrocarbons (PAHs) in samples of environmental origin. After separation by high-efficiency capillary liquid chromatography, the PAHs are detected by laser-induced fluorescence spectroscopy. Nitromethane is added to selectively quench the fluorescence of alternant PAHs, whereas diisopropylamine is added to quench nonalternant PAHs. The chromatograms in the absence and presence of fluorescence quenching are evaluated by means of the product moment correlation method to quantify the statistical similarities and differences. This method is demonstrated by application to three samples: a standard mixture of 16 priority pollutants, a coal-derived fluid, and a contaminated soil. The correlation coefficients (r) are typically 0.99 or higher for samples that are identical in origin, 0.90-0.50 for closely related samples, and less than 0.50 for samples that are distinctly unrelated. This method can be used to confirm with high statistical confidence the cause or source of an event with environmental impact, such as an oil leak or spill, contamination or waste by-products from petroleum fuel production and processing, etc.     

Low-density solvent-based solvent demulsification dispersive liquid-liquid microextraction for the fast determination of trace levels of sixteen priority polycyclic aromatic hydrocarbons in environmental water samples

For the first time, the low-density solvent-based solvent demulsification dispersive liquid-liquid microextraction was developed for the fast, simple, and efficient determination of 16 priority polycyclic aromatic hydrocarbons (PAHs) in environmental samples followed by gas chromatography-mass spectrometric (GC-MS) analysis. In the extraction procedure, a mixture of extraction solvent (n-hexane) and dispersive solvent (acetone) was injected into the aqueous sample solution to form an emulsion. A demulsification solvent was then injected into the aqueous solution to break up the emulsion, which turned clear and was separated into two layers. The upper layer (n-hexane) was collected and analyzed by GC-MS. No centrifugation was required in this procedure. Significantly, the extraction needed only 2-3 min, faster than conventional DLLME or similar techniques. Another feature of the procedure was the use of a flexible and disposable polyethylene pipette as the extraction device, which permitted a solvent with a density lighter than water to be used as extraction solvent. This novel method expands the applicability of DLLME to a wider range of solvents. Furthermore, the method was simple and easy to use, and some additional steps usually required in conventional DLLME or similar techniques, such as the aforementioned centrifugation, ultrasonication or agitation of the sample solution, or refrigeration of the extraction solvent were not necessary. Important parameters affecting the extraction efficiency were investigated in detail. Under the optimized conditions, the proposed method provided a good linearity in the range of 0.05-50 μg/L, low limits of detection (3.7-39.1 ng/L), and good repeatability of the extractions (RSDs below 11%, n=5). The proposed method was successfully applied to the extraction of PAHs in rainwater samples, and was demonstrated to be fast, efficient, and convenient.     

Application of a polysiloxane-based extraction method combined with column liquid chromatography to determine polycyclic aromatic hydrocarbons in environmental samples

Silicone rods with a diameter of 1 mm and 10 mm long were used to extract polycyclic aromatic hydrocarbons (PAHs) from water samples and for the rapid screening of highly contaminated waste material. The rods were placed in a 15 ml glass vial for the extraction of the analytes, which involved shaking (300 min⁻¹) the sample for 3 h. After extraction the rods were placed into 250 μl inserts of 2 ml vials filled with 100 μl of an acetonitrile-water mixture (4:1) and desorption was performed with sonication for 10 min. Then the PAHs were determined using LC and fluorescence detection. Recoveries of the rod extraction ranged between 62 and 97% and the detection limits were between 0.1 and 1.2 ng l⁻¹. These results are comparable with those of stir bar sorptive extraction (SBSE). Although the rods are reusable, their low price means they can be discarded if contaminated, eliminating the need for expensive cleaning. One disadvantage compared to SBSE is the longer extraction time needed to reach equilibrium.     

Graphene oxide bonded fused-silica fiber for solid-phase microextraction-gas chromatography of polycyclic aromatic hydrocarbons in water

A novel chemically bonded graphene oxide/fused-silica fiber was prepared and applied in solid-phase microextraction of six polycyclic aromatic hydrocarbons from water samples coupled with gas chromatography. It exhibited high extraction efficiency and excellent stability. Effects of extraction time, extraction temperature, ionic strength, stirring rate and desorption conditions were investigated and optimized in our work. Detection limits to the six polycyclic aromatic hydrocarbons were less than 0.08 μg/L, and their calibration curves were all linear (R(2)≥0.9954) in the range from 0.05 to 200 μg/L. Single fiber repeatability and fiber-to-fiber reproducibility were less than 6.13 and 15.87%, respectively. This novel fiber was then utilized to analyze two real water samples from the Yellow River and local waterworks, and the recoveries of samples spiked at 1 and 10 μg/L ranged from 84.48 to 118.24%. Compared with other coating materials, this graphene oxide-coated fiber showed many advantages: wide linear range, low detection limit, and good stability in acid, alkali, organic solutions and at high temperature.     

Application of copolymer coated frits for solid-phase extraction of poly cyclic aromatic hydrocarbons in water samples

A conducting copolymer of pyrrole and phenol was electrochemically synthesized on steel frits as a sorbent. The applicability of the frit was assessed for the solid-phase extraction of trace amounts of polycyclic aromatic hydrocarbons (PAHs) in aqueous samples followed by HPLC–UV. The coating produced was very adherent and the scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and FTIR spectrum for the coated frit were studied. The effects of various parameters on the efficiency of the solid-phase extraction process, such as the sample loading rate, elution solvent type, salt effect, volume and flow rate of sample and elution solvent were investigated. Under the optimal conditions, the calibration curves were obtained in the range of 0.1–500 ng mL⁻¹ (r² > 0.98) and the LODs (S/N = 3) were obtained in the range of 0.01–0.08 ng mL⁻¹. Relative standard deviations (RSDs) for intra- and inter-day precision were 2.7–10.2% and 3.6–11.4%, respectively. The recoveries (8 and 40 ng mL⁻¹) ranged from 79% to 115%. The simplicity of experimental procedure, short sample analysis, high extraction efficiency, and the use of low-cost adsorbent show the potential of this method for routine analysis of PAHs in real samples.